<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title></title>
    <meta name="viewport" content="width=device-width,user-scalable=0,initial-scale=1.0">
    <style media="screen">
    body {height:3000px;}
    .box {width:100px; height:100px; background:#CCC; position:absolute; left:0; top:0}
    </style>
    <script>
    window.onload=function (){
      let oBox=document.getElementsByClassName('box')[0];

      oBox.addEventListener('touchstart', function (ev){
        //存距离
        let disX=ev.targetTouches[0].pageX-oBox.offsetLeft;
        let disY=ev.targetTouches[0].pageY-oBox.offsetTop;

        ev.cancelBubble=true;
        ev.preventDefault();

        function fnMove(ev){
          oBox.style.left=ev.targetTouches[0].pageX-disX+'px';
          oBox.style.top=ev.targetTouches[0].pageY-disY+'px';

          //wp
          ev.preventDefault();
        }
        function fnEnd(){
          oBox.removeEventListener('touchmove', fnMove, false);
          oBox.removeEventListener('touchend', fnEnd, false);
        }

        oBox.addEventListener('touchmove', fnMove, false);
        oBox.addEventListener('touchend', fnEnd, false);
      }, false);
    };
    </script>
  </head>
  <body>
    <div class="box"></div>
  </body>
</html>
